Wireless telegraphy and telephone-receiving set



June 3 1924.

H. P. REES wmswss TELEGRAPHY AND TELEPHONE RECEIVING SET S i E mmh s June 3 19.24. 1,496,276

H. P. REES WTRE LESS TELEGRAPHY AND TELEPHONE RECEIVING SET Filed Aug. 9, 1921 s SheetS-Sheet 2 June '3 1924. 1,496,276

H. P. REES WIRELESS TELEGRAPHY AND TELEPHONE RECEIVING SET Filed Aug. 9 1921 3 Sheets-Sheet 3 Patented June 3, 192- 5.

IRE-LESS TELEGRAPHY AND TELEPHONE REGEIV'ING SET.

Application filed August 9, 1921. Serial No. 491,046.

(enanrnn UNDER ran PROVISIONS or THE Acr or MARCH a, 1921, 41 smart, 1313.

To all whom it may concern:

Be it known that I, HERBERT PERCY POWELL REEs, commonly known as HERBERT POWELL Times, a subject of the King of Great Britain, residing at 8 Grange Park, Ealing, in the county of London, England, have invented new and useful Improvements in lVireless Telegraphy and Telephone Receiving Sets (for which I have filed application in Great Britain dated 5th January, 1920, Patent No. 158,455), of which the following is a specification.

This invention relates to wireless telegraphy and telephony receiving instruments, and more particularly to a receiving set which is adapted to be tuned over a wide range of wave lengths.

One important object of the invention is to enable the receiving set to be made in a compact form and of small weight and nevertheless to be adapted for tuning over the said range to waves of the maximum length now in use. The receiving instruments or sets may therefore be constructed in a formsuitable for aeroplanes, exploring expeditions and the like where small weight and compactness are important considerations, and they may also be constructed in a form suitable for experimental work in places where space is restricted and portability is desired. The invention, however, is not confined to portable apparatus.

In receiving sets for long wave lengths, a considerable space has been occupied heretofore by the inductance coils, and their.

supports, and the apparatus has been consequently heavy. Various methods of winding coils, such as pile, basket and lattice winding, for the purpose of increasing the inductance and therefore wave-length obtained by a given length of conductor over that obtained by the ordinary single-layer cylindrical winding have been designed, but these expedients did not produce a coil of compact form and small weight, suchas is provided by these present improvements.

According to the present invention, a receiving set in which a thermionic valve is to be used, comprises a coil or coils wound in a so-ca'lled ring form so that the self-induc tion of such coil, or of each of the coils, is at, or as near as convenient to, the maximum which 'it is possible to attain with a conductor of given length, diameter and insulation thickness. That is to say, a coil to be comprised in the receiving set must have an axial length which is short in relation to its mean diameter with the turns in1a number of closely juxtaposed layers but not necessarily in any definite order. The normal damping effect of such a coil, on electrical oscillations is nullifed when the said coil is employed in combination with a thermionic valve or valves in such known relation that oscillations are regenerated and maintained in the circuits. V It has been known for many years-that maximum inductance could be 0btained-with a given length. of conductor of given diameter, and insulation thickness, by winding the conductor in the form ofva ring coil of certain dimensions. According to the Clerk- Maxwell formula, for example, maximum inductance is obtained, in the case of a coil the aggregate of turns of which are of square cross section, when the axial. length of the coil is approximately 10/37ths of its mean diameter.

By the employment of this form of coil, that is to saya coil of short axial length relatively to the mean diameter with the turns in aplurality of layers, in combination with a thermionic valve, the desirable result is achieved that waves of great length can be received by a receiving set of quite small weight and dimensions andthat the relatively large self-capacity is no hindrance but rather an advantage in the reception of such long waves, inasmuch as it increases the wave length obtained with a given length of conductor, without unduly flattening the tuning say from 2000 metres upwards. It is to be noted that for the purpose of obtaining good reception of signals on any wavelength when employing coils of small bulk and weight as aforesaid, the ring coils need not be of, or evenapproximate to, the dimensions conforming with the Clerlr-Maxwell formula, as it is found, for example, that ring coils of much shorter axial. length than that which would be givenby the said formula tune to much longer wavelengths for agiven'length of conductor and maintain their advantages of compactnes s,lightness and cheapness in comparison with. coils of the forms heretofore employed. It is to be further noted that such coils may be of any vshape, that 3 is? to say the. core of the length, which may be effected. The cross section of the aggregate of turns may also he circular. square. ovoid, oblong and so on. Such a coil may be bent to another desired shape after being in circular or other form. "he flexibility of dimensions and shape of such coils is frequently of advantage when designing instruments to fit into a space limited in any or all. of its dimensions and constitutes an additional advantage possessed by such coils over other forms of coils.

In a receiving set for tuning over a very wide range of wave lengths the inductance coils may be divided into two independent sets, and if desired, a third set may be pro vi'ded for use in tuning to the shorter wave lengths in the winding of which the axial length may be as short or even shorter than 3/37ths of the mean diameter and the insulation thickness of the conductor wire may be increased, by these means the self capacit is kept low while maintaining the iiiductance at a high figure in comparison with other forms of coil hitherto in use.

For the reception of the shorter wave lengths, it is sometimes advantageous not to couple the reaction coil with turns of the inductance coil in the aerial portion of the grid circuit but, instead, to couple it with inductance turns in a circuit connected with the aerial portion of the grid circuit.

A coil comprised in such combination may be sub-divided by tapping at required points. and this may be done during the winding by drawing out a. loop at each of the said points and continuing the winding uninterruptedly from each of the said points. The coils aforesaid may be not only iiuluctance coils in the aerial or grid circuit or in both but also the reaction coil or coils in the plate circuit.

In additionto the advantage of adaptability o 5 the said coils of smallbulk and weight for the reception of waves of any length. there is also the advantage that they can be wound very cheaply. It is only necessary to wind the required number of turns upon a rotating former without any particular de gree of care or skill, as it is immaterial whether or not the turns are wound in regular layers. Coils so wound may be removed from the former and bound, waxed or varnished to keep the turns in place, thus constituting a self supporting coil of high inductance, compact form and extreme lightness of weight.

In receiving sets, and particularly those designed to deal with a. wide range of wave lengths, a difficulty is commonly experi enced, when the inductance tuning switch is in some of the intermediate positions, due to interference with the tuned circuit by the overhanging part of the inductance. This overhanging part is that part which is not, for the time being, included in the tuned circuit. Owing to this peculiar interference, there are certain points, known as slip points where the continuity of the wave length curve on which oscillation is obtainable is broken so that oscillation on certain wave lengths is unobtainable. Means are provided in accordance with these improvements for avoiding this interference. For example, the aerial tuning switch may be adapted so that when it makes contact with a stud at one of these points, it also depresses an insulated stud or plunger, which opens a contact for cutting off entirely the overhanging part of the aerial inductance. However, owing to electrostatic interference, this expedient: is not always effective. Alternatively, therefore, the switch arm may be furnished with a second contact adapted for making contact with a second set of studs, so that at the critical points, one or more sections of the overhanging part of the aerial inductance is or are short-circuited and therefore thrown out of resonance.

The annexed drawing, forming part of this specification, illustrates examples of receiving sets embodying the present improvements, and therein:

Figure 1 is a diagrammatic plan of one construction of apparatus in which the whole of the apparatus is enclosed in a single box.

Figure 2 is a diagram of the circuits and connections of the apparatus seen in Figure 1.

Figure 3 is a diagrannnatic plan of a modified construction in which the apparatus is enclosed in three separate boxes A A and A Figures 4. 5 and 6 are diagrams of the circuits and connections of the apparatus seen in Figure as arranged for the reception of short, medium and long waves respectively.

Figure 7 is a plan of an inductance switch fitted with auxiliary means for short-circuiting the overhanging portion of the aerial inductance, and

Figure 8 is a sectional diagrammatic view of an inductance switch having one of its studs fitted with auxiliary means for cutting off the overhanging portion of the aerial inductance.

Referring to Figures 1 and 2, :3, B and B are inductance coils wound inaccordance In this position of'tlie-switch the; tan ce rB 'is place'd'in theaerjal circuitiand I is, connected to the grid h "of,thevz't'ilye l-l, -whilethe'reactidii coil C iscoiinected-up to i the electrode 7 iof the valve} H- andqto the teEphone-"circnit;"

provements, that is to say thesecoilsJar e' of ring form-as 18 shown by the sectional views of" the coils B, B C, B 'and C -These .coils are shown removed 't'ronr the box A for the sake of clearness'. I C and- C are, the

wound in the so-called'ring f orni and are coupled in a variable manner withthe coils B and B respectively. Forexample, and as shown in Figure l, the coils C,IC may be slidably adjustable-on the coils B B suitable finger rods C being-connectedwith these coils and extending to the' exteri'or of the'boX for this purpose. Alternatively,"

however, the coils C, ll1ay'5beirotatably adjustable in relation to the -"coi ls B aHdi in known manner. Dis: a Switch adjustable overa set oi'contacts"' d,--of"which twelve are shown numbered from l' to I 12 respectively, these contacts being connected: to vtappings of the inductance coils B,B i and B in the manner indicated by the correspondmg'nunibers on the connections jfromi these fcoils. The ta'ppingsl to 3 and 5 to 8- are formed by drawing out "loops from the conductor as itis wound to form the coils.

E is a three-pole two-way switch connectingv up either of the reaction coils C and'C" and either of the inductance -coils IB 1andlB according to the wave length to be received.

The coils B are additional inductance coils, 111561168 with the 0011 B F 1s a two-way switch connecting up the apparatus to avariable condenser G whichdby means of the said switch F, -may be-placedin parallel with the tuning inductance, asseen in--I=Eigure 2, or may be placedin series with the said inductance by reversing theswitch F.

,H is a thermionic valve having three electrodes in the example shown, the heating cells being marked it and connected to. the filament 7L1. J is a -telephone receiver in the high tension battery circuitK with condenser shuntk.

i In the particular arrangement illustrated,

the reaction coilC adjustably coupled with the inductance coil B is used fonshort waves only and for thispurposethesvvitch E is moved over to theleft in F igure 1, thereby cutting out the coils 13,13 and: C, and the switch D ismoved over on-to any "one of the contact st1ids1,-2, 3 or-4E according to whether a part only of the coil-B or 7 h of the valve.

-Eon-waves of medium. length, the induci tance coiLB? is brought into circuit by mov ng over the switch E into the position shown 1n the diagrams and by moving the switch D at the same time on to any one of the studs 5 to 9, the inductance coil B being correspondingly divided by tappings as reaction coils, which are preferably similarly shown insFigure 1.

-'The general arrangement of the circuits is thesamel as that already described for the short wave reception, excepting that the coils BPand'C are'now brought into circuit .in place of the coils B and C as seen in ;F1'gure. 2. To provide for a convenient factor oficoupling of the plate circuit with the grid circuit, however, the coil C may v-also betapped at one or more points, and

inthe arrangement shown a single tapping the telephone receiver J shown in Figure 2' and the terminals are connected up to the high tension battery-IQ, while the terminals b belong to the low tension battery I The aerial N is connected to the terminal n, while the terminal 0 is connected to the earth 0.

The circuit for long. wave reception is substantially the same 7 as that already described, but the switch D is moved over on to one or other of the studs (Z 10 to 12,

bringingin one, or more of the inductance coilsiBl Three such coils are shown in Figployed tapped at different points, but it is usually'more' convenient to employ a series of, coils of the, type already described.

In order, to prevent the interference of the overhanging portion of the inductance "coils B at the slip points aforesaid, and so that the continuityof the wave length curve is ensured,afsecond set of studs (Z may be provided concentric with the set (i, the switch arm D making contact with studs of both sets. It the studs at the positions 7 and: 8 are. the critical fstuds,the correspondthe'who'le ofthis coil is to be placed in'cir- .cuit. [The four studs allowbf tour -different inductance'valjues; for the coi1 B aciiigstuds in the'set d are connected by the connection (Z with, for example, the stud at =Ilzinwthe set (Z. 'The refore,'when the switch ved.

arm-Diis adjustedi'to either the stud 7 or Stud 8, a'portion of the inductance coils B,:'B that is to' say thatcportion lying between the studs 7 or 8Yand11,flis short-circuited' by the connection (1 stud in the set [Z and the arm 1D. If desired, and asshown in Eigu-re 7, the whole of thefloverhanging portion of the inductance coils'B, in any position of the switch arm D, between studs 4 and 12, may be short-circuited by connecting the end stud at 12 of the set d with the switch arm D as by the connection (Z The permanent connection of coils B and B to the earth thus made, does not afiect the reception of signals on the short wave lengths. Or, as shown in Figure 8, the stud at a critical position may consist of a hollow cylindrical part (Z encircling a plunger (Z of insulating material, the said plunger resting upon a spring contact blade (Z which normally makes contact with the bottom of the hollow stud part d. If the hollow stud part and the spring blade (Z be connected up as terminals of two successive sections of a coil, it follows that when the switch arm D is depressed on to the hollow stud part d, it will depress the plunger cl and the spring blade (Z thereby breaking the connection between the successive sections aforesaid. By one or other of these arrangements, the unutilized portion of the aerial inductance is thrown out of resonance so that it does not interfere with the tuned aerial circuit.

It is to be understood that, while a particular type of circuit has beendescribed for purposes of illustration. the invention is not restricted to that type but may, for example, be also applied to a coupled aerial circuit instead of the plain aerial circuit shown in the diagrams in Figures 2, a, 5 and 6 or to circuits in which both grid and plate circuits are tuned, or in which only the latter is tuned.

In the modification of the apparatus illustrated by Figures 3 to 6, the various parts are contained in three separate compartments or boxes A A and A the coils in these boxes being connected up in differentways for the reception of short, medium and.

long waves, as will be described.

The box A contains a sectional inductance coil B and a sectional reaction coil G which can be variably coupled therewith, as by making it rotatably adjustable, as indicated in Figure 3. -These coils B C correspond respectively with the coils B and C of Figure 1. The desired number of sections of the coil B is brought into the receiving circuit by the switch arm D moving over the contact studs (i the latter being numbered 1 to 8 corresponding with the eight tappings of the coil B The coil C has one tapping giving two sections, one or both of which can be brought into circuit by the switch L The box A is provided with terminals 72/, and corresponding to the similarly marked terminals in Figure 1, and also with a terminal 01. connected to the aerial N. It is further provided with terminals a or adapted to be connected to corresponding terminals or, a belonging to the second box A the terminal n also being connected to a terminal a belonging to the second box which contains a three-pole three-way switch E The connecting up of the various coils for short, medium or long wave length reception is accomplished by adjusting the switch E to an appropriate position as will be described.

The box A contains a series of coils B tive'of which are shown, corresponding to the inductance coils B of Figure 1, and a switch D moves over contacts (i marked 0 to 6 for bringing into circuit the desired number of the coils B, these coils being out out entirely when the switch arm D is on the contact marked 0. The switch arm D also moves over a second set of studs oi some of which are connected by connections d with certain of the studs (Z in a manner somewhat difierent from that described in connection with the studs (Z (Z in Figure 1, as will be hereinafter explained.

The box A contains a small inductance coil 13 divided into a series of six windings in the example shown. The inductance coil B may be wound in the ordinary manner, that is, as a single layer on a tube within which may be fitted the usual variable tuning condenser. The switch D is moved over the contact studs 05 marked 0 to 6, in order to bring into circuit the desired number of windings to suit the wave length to be received and to cut out the windings entirely when moved on to the contact 0. The box A may contain the condenser Gr between the terminals n (connected across to the terminals n of the box A and (1 (connected to the'terminal a of the box A and to the earth 0 as shown).

Assuming that a short wave reception is desired, the switch E is put over to the left to the position seen in Figure 3. The cir cuits thus completed will be seen clearly by reference to Figure 4. The aerial N is connected up to the end of the inductance B through the terminals n, n middle arm of the switch E and terminals a, a the aerial oscillatory circuit continuing through a part or the whole of the inductance B, the switch D and the condenser G to earth. The switch D of the box A should preferably be placed on stud 5, to place a portion of the inductance B in the grid circuit as seen in Figure 4, and in this case the connection between a and a may be broken, also as seen in Figure 4:. In this circuit, it will be seen that the reaction coil'C is not coupled with an inductance coil in the aerial circuit, but. with the inductance coil B, which is in the grid circuit, which is found to be advantageous for the reception of short wave lengths.

For medium wave lengths, the switch E is turned to its middle position and an aerial oscillatory circuit is created, which is represented by the diagram in Figurefi. The inductance B is not now in use, but an appropriate number of sections of the inductance B is put into the aerial circuit by the switch D the connection between a and or being then closed as shown. The circuit from the aerial N is as follows: through terminals 02-, n first or left hand arm of switch E terminals n n switchD placed on stud 0) terminals a a, middle arm of switch E and terminals a a the circuit then continuing through the inductance B switch arm D and terminals a a (L a to earth.

For long wave reception, the switch E is moved over to the right thereby producing the circuit connections represented by the diagram Figure 6. The switch arm D also may be placed over to the right, thereby putting into circuit the whole of the coils B From the aerial N, the circuit is through the terminals 12, n first arm of switch E terminals 11?, n switch arm D inductance B terminals a a", middle arm of switch E an appropriate number of sections of the inductance 13*, through the switch arm D which is set for connecting up the desired number of sections, through the third arm of the switch E terminals a a through a part or whole of the inductance B through switch arm D and terminals a 0;, a, a to earth.

It will be seen from Figure 3 that there are five coils, B and seven studs in the sets (Z and d numbered 0 to 6, the studs 2 and 3 in the set (F being connected together so that they are both terminals of the second of the coils 13*. It will be seen further, that the mode of cross connecting studs in the series d and d is as follows The No. 1 stud in the set al is connected with the connected Nos. 2 and 3 studs in the set 0Z Therefore, when the arm D is on the No. 1 studs, that coil at B which is between 0 and 1 is cut in and the coil between 1 and 2 is short-circuited by the connection d. This avoids a slip point which would otherwise occur during the tuning upwards in the wave-length range by means of the condenser G. When the arm D is on the No. 2 studs, the coils between studs0 and 2 are cut in and the coils between 2 and 4: are shortcircuited. Now the stud 3 in the set (i is the terminal of the same inductance coil at B as the stud 2, so that when the arm D is put on the No. 3 studs the coils between studs 0 and 2 are out in but no short-circuiting of another coil occurs, as is the case when the arm D is on the studs No. 2.

It is to be understood that the invention is not limited to the practical examples herein described with reference to the drawings, but that various changes and modifications can be made without departing from the essentialfeatures as herein stated and de fined by the claims.

I claim'i 1. Radio receiving set comprising in combination an antenna tuning coil comprising a plurality of layers, each layerconsisting of a plurality'of substantially plane turns, the axial length of said coil being short in re- .lation to its mean diameter, a holder for a three electrode vacuum tube, connections to said holder forming a grid circuit and con nections to said holder forming an anode circuit reactively coupled with said grid circuit. 1

2. Radio receiving set for use with a three electrode vacuum tube comprising in combination an antenna tuning coil having an axial length which is short in relation to its mean diameter, the turns of said coil being in a plurality of layers, each consisting of a plurality ofsubstantially plane turns, connections forming a grid circuit for the vacuum tube and connections forming an anode circuit for the vacuum tube reactively coupled with said grid circuit.

3. Radio receiving set comprising in combination an antenna tuning coil having an axial length which is short in relation to its mean diameter, the turns of said coil being in a plurality of layers, each consisting of a plurality of substantially plane turns, a three electrode vacuum tube holder, anode grid and cathode terminals mounted in said holder, connections between said grid terminal and said cathode terminals forming agrid circuit for the three-electrode vacuum tube, connections between said anode terminal and said cathode terminals forming an anode circuit for said vacuum tube and a reaction coil in said anode circuit coupled with said antenna tuning coil.

4. Radio receiving set comprising in combination, an antenna tuning coil having an axial length which is short in relation to its mean diameter, the turns of said coil being in a plurality of layers, each layer consisting of a plurality of substantially plane turns, a three-electrode vacuum tube holder, a three electrode vacuum tube supported in said holder, connections between the grid and cathode of said tube forming a grid circuit, connections between the anode and cathode of said tube forming an anode circuit and a reaction coil coupled with said antenna tuning coil and connected in said anode circuit, said reaction coil having an axial length which is short in relation to its mean diameter and being composed of a plurality of closely juxtaposed layers, each layer consisting of a plurality of substantially plane turns.

5. Radio receiving set comprising in combination, an antenna tuning coil having an axial length which is short in relation to its mean diameter, the turns of said coil being in a plurality of layers, each layer consisting of av plurality of substantially plane turns, a three-electrode vacuum tube holder, a threeelectrode vacuum tube supported in said holder, connections between the grid and cathode of said tube forming a grid circuit, connections between the anode and cathode of said tube forming an anode circuit and a reaction coil connected in said anode circuitand movably mounted relatively to said antenna tuning coil to enable the coupling tl'icrebetween variable, said reaction coil having an axial length which is short in relation to its mean diameter and being composed of a plurality of closely juxtaposed layers, each layer consisting of a plurality of substantially plane turns.

6. Radio receiving set comprising in co1nbination, connections forming an antenna circuit, a three electrode vacuum tube, connections forming a grid circuit for said tube, connections forming an anode circuit for said tube, a connection for impressing potentials upon the grid of said tube in accordance with oscillations in said antenna circuit, an inductance coil of ring form composed of a plurality of layers, each layer consisting of a plurality of turns, a switching, device adapted to connect said coil alternately in said antenna circuit or in the grid circuit of said tube and a reaction coil included in the anode circuit of said tube and coupled with the said coil.

7. Radio receiving set comprising in combination an antenna tuning coil having its axial length short in relation to its mean diameter and consisting of a plurality of layers, each layer consisting of a plurality of substantially plane turns, said coil having a plurality of taps, a three electrode vacuum tube, grid and anode circuits connecting respectively the grid and cathode of said tube and the anode and cathode of said tube, a reaction coil included in said anode circuit and variably coupled with said antenna tuning coil, a switching device for connecting any desired tap of said antenna tuning coil to the antenna circuit and an auxiliary switching device operatively connected with said firstnamed switching device for short-circuiting the portion of the antenna tuning coil not connected in said antenna circuit when said first-named switching device is placed in one of its operative positions.

H. POWELL REES. 

